Use the following model of a eukaryotic transcript to answer the question.E_1-4 refer to the exons,and I_1-3 refer to the introns in the pre-mRNA transcript.
5' UTR E₁I₁ E₂ I₂E₃I₃E₄ UTR 3'
Suppose that exposure to a chemical mutagen results in a change in the sequence that alters the 5' end of intron 1 (I₁) .Which of the following results might occur?

Question

Quizplus · Accepted Answer

Inclusion of I₁ in the mRNA is the most likely result of a change in the sequence that alters the 5' end of intron 1 (I₁). This is because the 5' end of an intron is recognized by the spliceosome, which is responsible for removing introns from the pre-mRNA transcript. If the 5' end of intron 1 is altered, the spliceosome may not be able to recognize it, and as a result, intron 1 may not be removed from the pre-mRNA transcript. This would lead to the inclusion of I₁ in the mRNA, which would result in a non-functional protein.

Use the Following Model of a Eukaryotic Transcript to Answer